ePESSTO spectroscopic classification of optical transients

ATel #11476; A. Floers, S. Taubenberger (ESO), C. Vogl (MPA), A. Pastorello, S. Benetti (INAF-Padova Observatory), L. Galbany (Pittsburgh), C. Gall (DARK, KU), J. Lyman (Warwick), Z. Kostrzewa-Rutkowska (SRON/RU), G. Leloudas (DARK), C. Inserra (Southampton), E. Kankare (QUB), K. Maguire, S. J. Smartt (QUB), O. Yaron (Weizmann), D. R. Young (QUB), J. Tonry, L. Denneau, A. Heinze, H. Weiland (IfA, Univ. of Hawaii), B. Stalder (LSST), A. Rest (STScI), K. W. Smith, O. McBrien (QUB), D. E. Wright (Univ. of Minnessota), K. C. Chambers, H. Flewelling, M. Huber, T. Lowe. E. Magnier, A. Schultz, C. Waters, R. J. Wainscoat, M. Wilman (IfA, Univ. of Hawaii)
on 25 Mar 2018; 18:17 UT
Distributed as an Instant Email Notice Supernovae
Credential Certification: Andrea Pastorello (andrea.pastorello@oapd.inaf.it)

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ePESSTO, the extended Public ESO Spectroscopic Survey for Transient Objects (see Smartt et al. 2015, A&A, 579, 40; http://www.pessto.org ), reports the following supernova classifications. Targets were supplied by the ATLAS survey, see Tonry et al. (2011, PASP, 123, 58) and Tonry et al. (ATel #8680), the Pan-STARRS Survey for Transients (see Chambers et al. 2016, arXiv:1612.05560, and http://pswww.ifa.hawaii.edu ), the ESA Gaia Photometric Science Alerts Team and DPAC (http://gsaweb.ast.cam.ac.uk/alerts), and the All Sky Automated Survey for SuperNovae (ASAS-SN; see Shappee et al. 2014, ApJ, 788, 48 and http://www.astronomy.ohio-state.edu/~assassin/index.shtml ). All observations were performed on the ESO New Technology Telescope at La Silla on 2018 March 25 UT, using EFOSC2 and Grism 13 (3985-9315A, 18A resolution). Classifications were done with SNID (Blondin & Tonry, 2007, ApJ, 666, 1024) and GELATO (Harutyunyan et al., 2008, A&A, 488, 383). Classification spectra and additional details can be obtained from http://www.pessto.org (via WISeREP) and the IAU Transient Name Server.

 
Survey Name | IAU Name    | RA (J2000)  | Dec (J2000)  |   Disc. Date   |  Source |  Discovery Mag. |    z     |  Type |    Phase   | Notes 
ATLAS18mmu  | SN 2018aii  | 12 22 10.41 | +26 59 40.44 | 2018 01 15.67  | ATLAS   | 20.3: (o-ATLAS) | 0.079164 |  Ic:  | around max | (1) 
PS18nh      | SN 2018alv  | 11 44 40.51 | +13 33 44.09 | 2018 03 19.35  | PS1     | 19.31 (w-PS1)   | 0.11     |  Ia   | before max | (2) 
Gaia18arh   | SN 2018ajz  | 11 37 42.18 | -49 10 43.14 | 2018 03 19.14  | Gaia    | 18.65 (G-Gaia)  | 0.016912 |  II   | +10d       | (3)    
ASASSN-18gf | SN 2018aly  | 15 01 57.33 | +25 46 15.96 | 2018 03 24.26  | ASAS-SN | 17.8 (g-Sloan)  | 0.044604 |  Ia   | after max  | (4) 

(1) The spectrum of ATLAS18mmu resembles that of the Type Ic SN 2004aw (Taubenberger et al. 2006, MNRAS, 371, 1459) at the light curve peak. However, it also shares some similarity with the spectra of 1991T-like SNe slightly before the maximum light. In both cases, the phases inferred from the spectral comparisons are inconsistent with the earliest marginal detection reported by the TNS, while is more consistent with the first multiple ATLAS detections on March 6, 2018. The expansion velocity of the SN ejecta, derived from the minimum of the Si II 635.5 nm line, is about 10500 km/s. The redshift of the host galaxy, 2MASX J12221040+2659401, is obtained from the Sloan Digital Sky Survey Data Release 6. A narrow absorption feature of Na I at the redshift of 2MASX J12221040+2659401 indicates some internal reddening.
(2) The spectrum of PS18nh matches that of a normal Type Ia SN a few days before the B-band maximum light. The redshift of the host galaxy is obtained from the positions of the broad SN features. The expansion velocity of the SN ejecta, as inferred from the minimum of the Si II 635.5 nm line, is about 12300 km/s.
(3) The spectrum of Gaia18arh is similar to that of the Type II-P SN 1999em (Elmhamdi et al. 2003, MNRAS, 338, 939) about 10 days after the explosion, and is dominated by H lines with broad P Cygni profiles. He I 587.6 nm is also detected. The expansion velocity of the SN ejecta derived from the FWHM of the Halpha emission is 11900 km/s, while from the position of the minimum of the Hbeta absorption, we obtain a velocity of about 6500 km/s. The redshift of the host galaxy, ESO 216- G 024, is from Fisher et al. 1995, ApJS, 100, 69.
(4) The spectrum of ASASSN-18gf is similar to that of normal Type Ia SNe soon after the B-band maximum light. The expansion velocity of the SN ejecta, as inferred from the position of the minimum of the Si II 635.5 nm line, is about 9400 km/s. The redshift of the host galaxy, 2MASX J15015731+2546168, is from Sanchez Almeida et al. 2011, ApJ, 735, 125. A narrow absorption feature of Na I is observed, suggesting significant extinction in the host galaxy.